Mustard oils, formed from

Upon heating the diarylthiourea with concentrated hydrochloric acid, it is partly converted into the aryl isothiocyanate (e.g. phenyl isothiocyanate or phenyl mustard oil, Expt 6.98, Method 1). A little hydrogen sulphide is evolved in a side reaction forming diphenylcarbodi-imide (4) which undergoes nucleophilic addition of aniline to yield triphenylguanidine (5), isolated from the reaction mixture as the hydrochloride. 

Use of cinnamon complexed with cyclodextrin in the manufacture of dried cinnamon-flavored apple slices prevents loss of cinnamon due to evaporation and protects the cinnamon from oxidation.100 Good flavor is released on consumption of the apple slices. Mustard oils are very irritating and care must be taken while working with them to prevent their release into the atmosphere. Complexing mustard oils with cyclodextrin reduces their volatility, making them easier to work with. While the volatility of the mustard oil is greatly reduced when it is in the complexed form, the mustard oil is readily released in the mouth when consumed. A complex of mustard oil has been used to prepare steak sauce.101... 

The method of making lewisite was suggested by the analogous method of mustard-gas manufacture used by the Allies. Thus, mustard is formed by the action of ethylene on sulfur monochloride, while lewisite is produced by action of acetylene on araeme trichloride in the pieaenct of aluminum trichloride acting as a catalyst. The dark brown viscid liquid a hich results from this latter reaction is decomposed by treatment with hydrochloric acid at O C. (32 F.), and an oil is obtained which < an be fractionated by distillation in vacuo into three chlor inyl derivatives of arsenic trichloride. These derivatives, which differ from each other only by the successive addition to the arsenic trichloride of one, two, or three molecules of acetylene, are as follows (see Chart Xlll) ... 

Mustard oils. Name for organic isothiocyanates, R-N=C=S, occurring in the essential oils of plants, mainly Brassicaceae, as the components responsible for sharp odors and pungent tastes. They exist in the plant in glycosidically bound form (see glucosinolates) and are released from the latter by tbioglycosidases (myrosinases) and subsequent rearrangements. 

In temperate regions, oilseed rape (Brassica napus L.) and turnip rape (Brassica campestris L.) predominate, while in the semitropics of Asia B. campestris and Indian mustard [Brassica juncea (L.) Czern.] are major vegetable oil sources. The English word rape, as it applies to the oilseed forms of B. campestris and B. napus, has arisen from the Latin word rapum, meaning turnip. The word mustard was derived from the European practice of mixing the sweet "must" of old wine with crushed seeds of black mustard [Brassica nigra (L.) Koch.] to form a hot paste, "hot must" or "mustum ardens", hence the modern term mustard (Hemingway, 1976). 

Crotonic acid was discovered in croton seeds by Pelletier and Caventou by saponifying the oil, adding tartaric acid, and distilling, but was more definitely characterised by T. Schlippe. Crotonitrile C4H5N, present in crude mustard oil, yields on hydrolysis with alcoholic potash crotonic acid C4He02, and crotonitrile is formed from allyl iodide and potassium cyanide hence the acid was formulated CH2 = CH-CH2 C02H. An isomeric acid was discovered by A. Geuther in the form of an acid chloride in the products of the action of phosphorus pentachloride on acetoacetic ester. 

Glucosinolates are thioglucosides. They contain a C=N-group substituted with sulfate and a residue R in anti position, as well as a sulfur atom connected with a /3-D-glucopyranosyl moiety (Table 44). At hydrolysis they liberate glucose, sulfate and an unstable aglycon. From the latter isothiocyanates (mustard oils), thiocyanates, nitriles, or cyanoepithioalkanes may be formed. 

Gadamer i-ecommends the following process. The mustard oil is dissolved in alcohol to form an exactly 2 per cent, solution. Five c.c. (4 2 gi-ams) of this solution are allowed to remain with 25 c.c. of deci-noi-mal solution of silver nitrate and 5 c.c. of ammonia for twenty-four hours in a well-stoppei-ed 50 c.c. flask. It is then made up to 50 c.c. with water and filtered from the precipitated silver sulphide 25 c.c. of the filtrate are mixed with 4 c.c. of nitric acid and a few drops of ferric sulphate solution, and titrated with deci-normal ammonium thiocyanate solution, until the characteristic red colour of the ferric thiocyanate appears. 

The effectiveness of the method is most probably based on the fact that alkyl hypochlorite is formed at the oil/water interface where the cosurfactant alcohol resides. The oxidation that follows takes place either inside or on the surface of oil droplet. The rate of the reaction can result from a large hydrocarbon/water contact area permitting interaction between oil-soluble sulfide with interfacial cosurfactant that served as an intermediary. An extension ofthis procedure to mustard deactivation has also been proposed [20b]. Such systems could be also applied to the degradation of several environmentally contaminating materials The formation of microemulsions, micelles and vesicles is promoted by unfavourable interactions at the end sections of simple bilayer membranes. There is no simple theory of solute-solvent interactions. However, the formation of... 

Oil of Mustard.—Only the last compound named is important, viz., allyl iso-thio-cyanate, CH2 = CH—CH2NCS. Strange as it may seem, from statements made in connection with the cyanates and iso-cyanates of the saturated series, this compound is made by treating allyl-iodide, not with silver thio-cyanate, but with potassium thio-cyanate. As, however, the tautomeric iso-compounds are made from the cyanates and thio-cyanates by heat, the conversion of the first formed thio-cyanate into the iso-thio-cyanate can readily be understood. 

Some plants from which volatile oils may be distilled do not contain the oil as such, but contain certain basal substances, which, under proper conditions, react with one another to form the oil. The oil may then be removed by the usual process. Examples of such oils are winter-green, sweet birch, bitter almond, and mustard. The chemical reaction that results in the formation of these oils is readily induced by simply macerating the material or soaking the ground or chopped material with water for a suitable period, after which distillation may proceed. The material is usually macerated in the tub of the still, so that no transfer of the mixture is necessary. 

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